Imaging features of TSC2/PKD1 contiguous gene deletion syndrome in adults.

OBJECTIVES: To report the first detailed description of the radiological features of tuberous sclerosis complex 2/polycystic kidney disease 1 (TSC2/PKD1) contiguous gene deletion syndrome (CGS), a rare and poorly reported or described syndrome. METHODS: This multicenter retrospective study included 9 adult patients (6 women, 3 men; mean age, 29±8 years) with genetically confirmed TSC2/PKD1 CGS. Clinical data and imaging studies (MRI, CT, ultrasound) were reviewed independently by two radiologists. Radiological features assessed included kidney length, total kidney volume (TKV), height-adjusted TKV (hTKV), cyst burden, angiomyolipomas (AMLs), and extrarenal manifestations. RESULTS: All patients presented with enlarged polycystic kidneys (mean TKV: 2134 ± 904 mL; mean hTKV: 1260 ± 471 mL/m) and a high cyst burden (median 45 cysts per kidney); 7 of 8 classifiable patients (88%) were assigned to Mayo imaging class 1E, a classification validated in ADPKD whose prognostic value cannot be directly transposed to CGS, where renal volume also reflects solid angiomyolipomatous tissue. AMLs were observed in 78% of cases, with both fat-rich and fat-poor subtypes. One patient developed a hemorrhagic AML requiring embolization and underwent nephrectomy for a growing fat-poor lesion, ultimately diagnosed as AML. End-stage renal disease occurred in 67% of patients at a median age of 25 years. Extrarenal findings included cerebral cortical tubers and subependymal nodules in all patients, hepatic cysts (56%), hepatic AMLs (33%), pulmonary lymphangioleiomyomatosis (22%), and cardiac rhabdomyomas (22%). CONCLUSION: Adult patients with TSC2/PKD1 CGS exhibit a distinct imaging phenotype characterized by features of both ADPKD and TSC. The identification of AML in the context of ADPKD-like cystic disease should prompt consideration of CGS. Early diagnosis is crucial for guiding appropriate follow-up, therapeutic interventions, and genetic counseling.